The invention concerns a method and an apparatus for folding a resilient intraocular lens.
When a cataract operation is performed, an intraocular lens comprising a resilient material such as more particularly silicone is inserted in a folded condition into the natural eye capsule which has remained in the eye. In that respect the operation of putting the intraocular lens into a folded condition is often a really troublesome procedure as, during the folding operation the resilience of the lens means that the lens frequently jumps out from between the two gripping elements of the implantation instrument which is normally in the form of a tweezer-like instrument. That occurs whenever the resilient lens body is not exactly positioned between the gripping elements of the implantation instrument.
More specifically, various forms of a surgical device for the implantation of deformable intraocular lenses are to be found in German patent specification No. 3 348 066. In one embodiment of such a device, two elongate jaws which are movable in opposite relationship to each other co-operate to form a closed cavity which serves to receive the compressed or folded intraocular lens. With that device, the intraocular lens is clamped in widely varying forms between the elongate jaws, with the lens being disposed therebetween in a somewhat random fashion. It is not possible to exclude the possibility of damage occurring when the intraocular lenses are handled in that way. In addition problems occur upon operative intervention in the eye as the lens comes out of the device in a relatively uncontrolled fashion, depending on the way on which it was randomly disposed between the two jaws. Furthermore, the fact that the lens has to be manually introduced into the device means that the medical personnel carrying out that operation have to meet relatively high demands in terms of their skill in carrying out that operation.
Another device described in the above-indicated patent specification has a chamber for receiving the undeformed intraocular lens, and the intraocular lens can be pressed into the eye by means of a pressure agent through an outlet opening of very small cross-section. With that device the lens is also pressed through the outlet opening in an arbitrary fashion for, depending on the way in which the lens comes to lie in front of the outlet opening in a random configuration, it will tend to be folded together in an undefined fashion. It will be appreciated that that means that the lens cannot issue from the instrument and pass into the eye in a defined uniform fashion. Damage to the sensitive intraocular lens when it is being pressed through the narrow outlet opening is also a possibility which cannot be excluded.